The problem is not the [Addon]Windows Sidebar v6.0.6001.18000, the problem is the file inf, for example with the [Addon]InterDownloadManger5.15 Build 4 (International) I have the same error. [ INF Install failure. Reason: Could not retrieve the system message. You may run out of the system resource. ] Post = [Addon]InterDownloadManger5.15 Build 4 (International)